Seeking other Earths

Twinearth[cross posted from KySat blog]

According to SpaceDaily, exoplanetologists may now be able to detect another Earth in orbit around distant stars using a specially rigged telescope. In a successful demonstration of the technique, NASA researchers have shown that the method can make out the image of an Earth-like planet that would ordinarily be overpowered by the light emitted from its star.

'Our experiment demonstrates the suppression of glare extremely close to a star, clearing a field dark enough to allow us to see an Earth twin. This is at least a thousand times better than anything demonstrated previously,' said John Trauger, lead author of a paper appearing in the April 12 issue of Nature. This paper describes the system, called the High Contrast Imaging Testbed, and how the technique could be used with a telescope in space to see exoplanets. The lab experiment used a laser as a simulated star, with fainter copies of the star serving as 'planets.'

To date, scientists have used various techniques to detect more than 200 exoplanets. Most of these exoplanets are from five to 4,000 times more massive than Earth, and are either too hot, too cold or too much of a giant gas ball to be considered likely habitats for life. So far, no one has managed to capture an image of an exoplanetary system that resembles our own solar system. Scientists are eager to take a closer look at nearby systems, to hunt for and then characterize any Earth-like planets - those with the right size, orbit and other traits considered friendly for life.

In the lab demonstration, the High Contrast and Imaging Testbed overcame two significant hurdles that all telescopes face when trying to image exoplanets - diffracted and scattered light.

The image above, contained in the NASA/JPL press release, shows three simulated planets. One is as bright as Jupiter, one half as bright as Jupiter and the other as faint as another Earth might appear. The asterisk marks the location of the system's simulated star.